As a first step, we use storage data to parametrize the initial SEI thickness \(L_{\text{SEI},0}\)  and the diffusivity \(D_{\text{e}^\text{-}}(T={30}{})\) , see Equation REF . In this case, we solve Equation REF  analytically, because the SEI overpotential \(\eta _\text{SEI}\)  is constant in time. This leads to the well-known \(\sqrt{t}\) -dependence of SEI growth during battery storage [1]}
\(L_\text{SEI}= \sqrt{2\frac{c_{\text{e}^\text{-},0}D_{\text{e}^\text{-}}(T) \bar{V}_\text{SEI}}{\nu _\text{SEI}}e^{-\frac{F}{RT}U_0}t+L_{\text{SEI},0}^2}.\) 
